Nowadays inkjet printing systems are used in a wide array of apparatuses in a wide array of applications such as fax, colour photo printing, industrial applications etc. In these printing systems inks, possibly of various colours, are ejected out of at least one array of nozzles located in a print head onto a receiving material.
A long known problem in inkjet printers is that the nozzles through which the ink is projected to the receiving material are blocked by clogging of ink inside the nozzles and on the print head. This renders certain nozzles inoperable and results in a defective print or deteriorated print quality.
To improve the clarity and contrast of the printed image, recent research has been focused to improvement of the used inks. To provide quicker, more waterfast printing with darker blacks and more vivid colours, pigment based inks have been developed. These pigment-based inks have a higher solid content than the earlier dye-based inks. Both types of ink dry quickly, which allows inkjet printing mechanisms to form high quality images.
In some industrial applications, such as making of printing plates using ink-jet processes, certain inks having special characteristics, for example, UV curable inks exist to allow rapid hardening of inks after printing.
The combination of small nozzles and quick drying ink leaves the print heads susceptible to clogging, not only from dried ink and minute dust particles or paper fibres, but also from the solids resident within the ink.
It is known to counteract or correct the problem of clogging by protecting and cleaning the print head by various methods.                Wiping: Before and during printing, the inkjet print head is wiped clean by using an elastomeric wiper, removing ink residue, paper dust and other impurities.        Capping: during non-operational periods the print head can be sealed off from contaminants by a sealing enclosure. This also prevents the drying of the ink. The capping unit usually includes a rubber seal placed around the nozzle array.        Spitting: by periodically firing a number of drops of ink through, each nozzle into a waste ink receiver, commonly called a spittoon, clogs are cleared from the nozzles. This can be concentrated to nozzles which are not used for a certain time but usually all the nozzles are actuated during spitting.        Vacuum assisted purging: During a special operation, in order to clear partially or fully blocked nozzles, a printing is actuated while on the outside of the nozzles a vacuum is applied. This helps clearing and cleansing the nozzles. The purging is normally performed when the print head is in the capping unit because this unit can provide a good seal around the nozzle array for building the vacuum.        
Also other methods exist for cleaning an inkjet print head which may include applying solvents.
These features designed to clean and to protect a print head, are commonly concentrated in a service station which is mounted within the plotter chassis, whereby the print head can be moved over the station for maintenance. An example of such a service station with combined wiping, capping, spitting and purging functions can be found in U.S. Pat No. 6,193,353 herein incorporated by reference in its entirety for background information.
It is inherent to the purging action that a relatively large amount of ink is used. The firing of the nozzles is usually done by actuating all the nozzles at the same time but a sequential actuation of the print elements can also be used.
The ink can be drained from the capping enclosure by the same vacuum source which provides the vacuum for purging. Also alternative systems for removing the ink from the capping enclosure can be provided.
After purging, an excess amount of ink remains on the exterior side of the print head, especially on the nozzle plate. In order to use the print head for recording, a wiping action is performed before printing is started. A wiper passes along the printing surface of the print head.
However several problems have been encountered during wiping after purging and during wiping in general.                Because of the large amount of ink remaining on the outside of the print head, the wiper does not have enough capacity to clean the print head in a satisfying manner. The large drops or blobs of ink can not be removed sufficiently.        A state of the art wiper consists of at least one elongated strip of elastomeric material having the length of the nozzle array, parallel with the array and is moved over the print head in a direction perpendicular to the direction of the nozzle array. Upon contact of the strip with the print head a considerable force is exerted upon the print head. As the elastomeric material will have a certain rigidity, a mechanical shock will be given to the print head as the whole length of the wiper simultaneously makes contact with the print head. This shock can disturb the normal equilibrium of the menisci in the nozzles of the print head. Mechanical shocks can even cause intrusion of air into the print head. Also the mounting means of the print head and the wiper can be affected by the shock.        During the wiping action the whole length of the wiper is slightly deformed as it is held in contact with the print head. The total force acting upon the print head and wiper system as they are kept in pressure contact with each other during the wiping action puts a lot of strain on the mounting assembly and moving mechanism of the print head and wiper system.        At the end of the wiping action the elastomeric strip reaches the end of the print head and suddenly recoils to its original position. This also generates a mechanical shock while at the same time the ink residues on the tip of the wiper, which are especially large during the first wiping step after purging, are flung away contaminating the inside of the printer.        
The result is that after purging normal wiping is insufficient while the wiping action using state of the art wipers gives rise to considerable mechanical stress leading to alignment errors and contamination of the printer.
After wiping, a large amount of ink can remain on the side of the print head forming a meniscus.
It is clear that several drawbacks have to be overcome.